Continental Drift Continental drift, and the subsequent theory of plate tectonics, forms the modern framework for geological study of the Earth. Continental drift stems from scientific notions as early as the 16th century that the Earth’s continents were once a single land mass, which scientists have termed Pangaea, meaning "all lands" in Greek. In 1912, German meteorologist Alfred Wegener proposed that natural forces such as earthquakes and floods broke Pangaea apart between 225 and 200 million years ago, and it eventually fragmented into the continents as we know them today. Wegener based his theory on four major observations: first, the amazing fit of the African and South American continents; second, the similarities of unusually structured plant and animal fossils discovered along the coastlines of South America and Africa, even though they are separated by the Atlantic Ocean; third, similarities in rocks and ice sheets on these two continents; and fourth, evidence that some ancient climates were diametrically opposite of modern ones. Wegener’s theory of continental drift would eventually spark a new way of viewing the Earth. Initially, however, colleagues generally dismissed it as absurd, despite the fact that it seemed to complement available scientific information. Their primary criticism was Wegener’s inability to adequately explain how the large masses of land could drift such great distances. ■(A) Wegener speculated that they simply plowed through the ocean floor, but English geophysicist Harold Jeffreys refuted that contention, noting that it is physically impossible for a gargantuan mass of solid rock to do so without breaking up. ■(B) It was not until the 1950s--two decades after Wegener’s death--that technological advances enabled scientists to confirm Wegener’s hypotheses. Improved techniques in ocean floor mapping revealed that the bottom of the ocean was not mostly flat and featureless as most scientists had speculated, and that geologic processes on land, such as earthquakes and volcanic eruptions, were linked to dynamics on the ocean floor. ■(C) Scientists discovered that hot rock boils up from the Earth’s mantle1 near ridges in the middle of the ocean, spreading over the sea floor and forming new oceanic crust. ■(D) As this crust spreads, it moves continents an average of one or two centimeters each year. Scientists also found that as new crust forms at ocean ridges, older crust descends into trenches2 at the rim of the Pacific Ocean Basin, effectively recycling the ocean basins and maintaining the Earth at a steady size. Seismic activity is most prominent in earthquake zones parallel to these trenches at the edge of continents, likely due to the fact that sinking crust melts, causing hot rock to bubble up, leading to eruptions and violent quaking. These findings on the ocean floor led to the theory of plate tectonics, which holds that the Earth’s outermost layer consists of more than a dozen large and small plates--massive slabs of solid rock, both above and beneath the water--that are drifting about the surface of the Earth, occasionally colliding, rubbing against each other, clustering and separating, and even disappearing completely under one another. These interactions are constantly shaping the face of the planet, signified by the term "tectonics" from the Greek word meaning "to build." The results of plate-tectonic forces are most evident at plate boundaries--narrow zones between plates. At divergent boundaries, plates pull away from each other, creating new crust. A prominent example can be seen in Iceland, which is splitting as the North American Plate moves westward relativeto the Eurasian Plate. At convergent boundaries, crust is destroyed as one plate dives under another. This tends to form mountain ranges on continental, or surface, plates, such as the South American Andes and the Asian Himalayas. At transform boundaries, plates slide horizontally past each other and crust is neither created nor destroyed. Since the plates lack smooth edges, pressure is generally built up and suddenly released, making these types of boundaries--such as the San Andreas Fault in California--particularly susceptible to earthquakes. At a fourth type of boundary, called plate boundary zones, there are broad areas where boundaries are ill-defined and the effects of plate interaction are not well understood. Because plate boundary zones feature at least two large plates and one small plate caught between them, they have complicated geological structures and earthquake patterns. The theory of plate tectonics has gained widespread scientific acceptance, though there still remains debate over specific aspects. One of these, ironically, is the same question that dogged Wegener: What is the nature of the forces propelling the plates
A．Constant regeneration of oceanic crust.B．Earthquakes and volcanic eruptions.C．The movement of divergent boundaries.D．Interactions at transform boundaries.
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甲公司于2008年发生经营亏损1000万,按照税法规定,该亏损可用于抵减以后5个年度的应纳税所得额。该公司预计其于未来五年能够产生的应纳税所得额为800万元。甲公司适用的所得税税率为25%,无其他纳税调整事项,则甲公司于2008年就该事项的所得税影响,应做的会计处理是( )。 甲公司于 2008 年发生经营亏损 1 000 万元,按照税法规定,该亏损可用于递减以后 5 各年度的应纳税所得额。 该公司预计其于未来 5 年间能够产生的应纳税所得额为为 800 万元。 甲公司适用的所得税税率为 25% ,无其他纳税调整事项,则甲公司 2008 就该事项的所得税 影响,应做的会计处理是( )
A. 确认递延所得税资产250万元 B. 确认递延所得税负债250万元 C. 确认递延所得税资产200万元 D. 确认递延所得税负债200万元
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